My 2nd great-grandfather is Samuel L. Erdahl. He lived about 3 mile noth of Rake, Iowa in Blue Earth Township, Minnesota. He had three wives. Oline Olsen died 1884 Synnove Berge died 1891 Hannah Møller-Pederson died 1946
I have seen Oline's name documented in the following manner Oline O. Erdahl Oline Olsen Serrina O. Erhahl Søvrine Oline Erdahl Syverine Oline Olsdatter
Sam and Oline had a daughter name Mathilda who married P. J. Erdal. They had a daughter named Inez who married Oscar Isackson. They also had two other daughters named Mae who married Frank Delyea and Adline, I have no record of her marriage.
My line is from Sam's third wife Hannah. Their oldest daughter Hilda married John Estebo. Hazel, their oldest, is my grandmother.
Does any of this match your data? Most, if not all of the Erdahls' and Erdals'in Iowa are related to me.